U-pipe velocity profile

mariam.sara · December 6, 2013, 02:30

Hi all i have flow through U-tube as shown in picture attached i want to draw the vertical velocity profiles in different sections a long the arc(i.e. with different angles which vary from 0 to 180) ? is that possible in fluent or i need to draw it by CFD-post? please tell me the details?
Thanks
mariam

flotus1 · December 6, 2013, 04:35

What exactly was wrong with the first answers you got?
Create lines at the locations where you want to plot the profiles, and then you plot them.
And yes, the same thing can be done in CFD post.
You will need to ask a more detailed question to get more detailed answers.

mariam.sara · December 7, 2013, 14:21

Thanks flotus for the answer. I want to plot vertical velocity profiles along the curvature but i have difficulty in determine the coordinates for points of start and end of the lines because I not have idea how to calculate or determine it?
may u help me how to set it please?
N.B. I want at least draw 10 lines along the u-pipe

Thanks

Zaktatir · December 8, 2013, 12:02

you have to define this lines!!!

In Post you may import file definitions of this polylines!!

mariam.sara · December 8, 2013, 13:59

Zaktatir thanks for answer. may you tell me what you mean with import the files definition of the polylines? may you give me an example about this thing?

Zaktatir · December 8, 2013, 14:19

I do not have any example look into documentation of Post or open Post and look for the option..

mariam.sara · December 8, 2013, 14:35

To be more specific at my question when i try to draw lines it request from me values for x,y,z start and x,y,z end points ? how i can determine these coordinates? is there away to determine it from screen? i want do this in FLUENT i not talk about CFD post now?

Quote:

Originally Posted by Zaktatir

I do not have any example look into documentation of Post or open Post and look for the option..

Zaktatir · December 8, 2013, 14:43

I talked about Post with polyline import...

I cannot imagine that you will be able to make this in fluent straightforward.

flotus1 · December 9, 2013, 03:38

Let me see if I got this. So what you want is to plot profiles of velocities and other variables over lines that may be described by the following picture:
lines.jpg
We dont need any curved lines, right?
You may select points for lines on the screen in fluent or even use the line tool to manipulate lines with the mouse. But this is neither exact nor very comfortable.

If the origin of the coordinate system you are using lies in the "center" of the u-pipe and the geometry is symmetric towards the xy-plane (see the picture I added to get the idea) this is quite easy.
The first point of the lines will always be (0/0/0), the second point can be determined using some trigonometry

$\begin{split} x=r \cdot cos(\phi)\\ y=r \cdot sin(\phi) \end{split}$

Here r is a radius that has to be larger than the the outermost part of your geometry. Dont worry if the lines are partly outside the geometry, fluent doesnt care about this.

If your geometry is not aligned this way, you should consider doing so or you will have to do some coordinate transformation to find the positions of the lines.

mariam.sara · December 10, 2013, 14:23

Thank you for the valuable answer and explaining flotus i will try your method it look fruitful.

Quote:

Originally Posted by flotus1

Let me see if I got this. So what you want is to plot profiles of velocities and other variables over lines that may be described by the following picture:
Attachment 27237
We dont need any curved lines, right?
You may select points for lines on the screen in fluent or even use the line tool to manipulate lines with the mouse. But this is neither exact nor very comfortable.

If the origin of the coordinate system you are using lies in the "center" of the u-pipe and the geometry is symmetric towards the xy-plane (see the picture I added to get the idea) this is quite easy.
The first point of the lines will always be (0/0/0), the second point can be determined using some trigonometry

$\begin{split} x=r \cdot cos(\phi)\\ y=r \cdot sin(\phi) \end{split}$

Here r is a radius that has to be larger than the the outermost part of your geometry. Dont worry if the lines are partly outside the geometry, fluent doesnt care about this.

If your geometry is not aligned this way, you should consider doing so or you will have to do some coordinate transformation to find the positions of the lines.

Zaktatir · December 10, 2013, 15:02

it would be very interesting if you may add some scripting for that but i suggest doing that in Post with Perl. Nevertheless i thought you want to define polylines and not straight lines the idea of flotus is then the best to follow

mariam.sara · December 17, 2013, 15:03

Hi flotus I tried what you recommended me but I discover the origin of my coordinates not lies at the center of the tube? you mentioned at your last post i need to find the coordinate transformation to find the positions of the lines? how i can do this thing please?

Mariam

flotus1 · December 17, 2013, 17:12

If you are working with fluent, the easiest thing would be to transform your mesh to have it in the right location. See the "mesh" menu item in fluent, it should have all the options you need (translate, rotate).

mariam.sara · December 17, 2013, 23:57

Hi in surface menu the only thing i found is surface transform the problem i have volume not surface when i tried to translate all surfaces it seems wrong? do i need first translate volume in gambit before export it to fluent?

flotus1 · December 18, 2013, 12:00

Quote:

See the "mesh" menu item

And as it was already mentioned some posts ago, instead of applying the mesh transformations in fluent, it would be even better to create the geometry/mesh in the correct position before starting fluent.

December 9, 2013, 03:38		#9
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	Let me see if I got this. So what you want is to plot profiles of velocities and other variables over lines that may be described by the following picture: lines.jpg We dont need any curved lines, right? You may select points for lines on the screen in fluent or even use the line tool to manipulate lines with the mouse. But this is neither exact nor very comfortable. If the origin of the coordinate system you are using lies in the "center" of the u-pipe and the geometry is symmetric towards the xy-plane (see the picture I added to get the idea) this is quite easy. The first point of the lines will always be (0/0/0), the second point can be determined using some trigonometry $\begin{split} x=r \cdot cos(\phi)\\ y=r \cdot sin(\phi) \end{split}$ Here r is a radius that has to be larger than the the outermost part of your geometry. Dont worry if the lines are partly outside the geometry, fluent doesnt care about this. If your geometry is not aligned this way, you should consider doing so or you will have to do some coordinate transformation to find the positions of the lines. mariam.sara likes this.

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December 6, 2013, 04:35		#2
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	What exactly was wrong with the first answers you got? Create lines at the locations where you want to plot the profiles, and then you plot them. And yes, the same thing can be done in CFD post. You will need to ask a more detailed question to get more detailed answers.

December 7, 2013, 14:21		#3
mariam.sara Senior Member Join Date: Jan 2011 Posts: 339 Rep Power: 16	Thanks flotus for the answer. I want to plot vertical velocity profiles along the curvature but i have difficulty in determine the coordinates for points of start and end of the lines because I not have idea how to calculate or determine it? may u help me how to set it please? N.B. I want at least draw 10 lines along the u-pipe Thanks

December 8, 2013, 12:02		#4
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	you have to define this lines!!! In Post you may import file definitions of this polylines!!

December 8, 2013, 13:59		#5
mariam.sara Senior Member Join Date: Jan 2011 Posts: 339 Rep Power: 16	Zaktatir thanks for answer. may you tell me what you mean with import the files definition of the polylines? may you give me an example about this thing?

December 8, 2013, 14:19		#6
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	I do not have any example look into documentation of Post or open Post and look for the option..

December 8, 2013, 14:43		#8
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	I talked about Post with polyline import... I cannot imagine that you will be able to make this in fluent straightforward.

December 10, 2013, 15:02		#11
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	it would be very interesting if you may add some scripting for that but i suggest doing that in Post with Perl. Nevertheless i thought you want to define polylines and not straight lines the idea of flotus is then the best to follow

December 17, 2013, 15:03		#12
mariam.sara Senior Member Join Date: Jan 2011 Posts: 339 Rep Power: 16	Hi flotus I tried what you recommended me but I discover the origin of my coordinates not lies at the center of the tube? you mentioned at your last post i need to find the coordinate transformation to find the positions of the lines? how i can do this thing please? Mariam

December 17, 2013, 17:12		#13
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	If you are working with fluent, the easiest thing would be to transform your mesh to have it in the right location. See the "mesh" menu item in fluent, it should have all the options you need (translate, rotate).

December 17, 2013, 23:57		#14
mariam.sara Senior Member Join Date: Jan 2011 Posts: 339 Rep Power: 16	Hi in surface menu the only thing i found is surface transform the problem i have volume not surface when i tried to translate all surfaces it seems wrong? do i need first translate volume in gambit before export it to fluent?